A few common practices that educational leaders should avoid.
1. Using possessive language
I am not a big fan of using terms such as "my teachers", "my school", or "my class." It is not that you shouldn't take ownership of your responsibilities, but you shouldn't want to "own" teachers, class, or schools - you should want to lead them. Ownership and leadership are not the same thing.
2. Manipulating the frame to get your way
Leaders, for the most part, view their situations from a few frames: structural, political, symbolic, and human resource (for more about these frames check out Reframing Organizations by Bolman and Deal). Effective leaders use more than one frame to view situations and make decisions. When the wrong frame is used to evaluate an issue, decisions may be misaligned to the actual problem and the decision is not as effective as it could have been. Another concern is when leaders manipulate the frame to promote their agenda instead of learning and adjusting their decisions. This is often the result of single frame use and the leader's desire to make a quick decision and move on. For example, a leader is asked if teachers can have a "casual day" on Friday makes a quick decision to say, "No." He is gently challenged and instead of trying to view the situation from the human resource frame (may be a good chance to lighten the mood after a particularly stressful week), symbolic frame (send the signal that we can learn and relax at the same time), or political frame (allowing the dress down day this week may earn some credit with the faculty I can use when we have a tough project facing us); he simply uses the policy manual (structural frame) to state faculty dress code and the need to follow policy.
Justifying a selfish decision by invoking a tangentially appropriate frame of reference is manipulation, not leadership.
3. Missing the trees for the forest
Yes, I know the saying goes "missing the forest for the trees" but I flipped this to highlight the point. In an effort to maintain a big picture view, you may find yourself feeling disconnected from the daily operations of the school. Take time to be among the students, greet families, and visit classrooms. I have found that my best "big picture" thinking occurs when doing those things anyway. The act of "recognizing the trees" helps focus on what is essential, thus ideas that emerge from observing the essentials are often the better ideas - they are not formed in a vacuum, they are formed from observations "in the field."
If you have any items to add to this list, feel free to leave a comment.